A new study, by Eunice S. Han for the The National Bureau of Economic Research, titled "The Myth of Unions’ Overprotection of Bad Teachers: Evidence from the District-Teacher Matched Panel Data on Teacher Turnover" found teachers unions raise the dismissal of low-quality teachers because higher wages give districts a greater incentive to select high-quality teachers but lower the attrition of high-quality teachers, as they negotiate higher wages for teachers.
From the study's conclusion:
I find that districts with strong unionism dismiss more underperforming teachers and have lower teacher attrition than districts with weak unionism.
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I find that districts with strong unionism dismiss more underperforming teachers and have lower teacher attrition than districts with weak unionism.Through the dynamics of teacher turnover, unions ultimately raise teacher quality, as unionized districts can better retain good teachers and dismiss more underperforming teachers. Two pieces of empirical evidence support this hypothesis: districts with strong unionism have more teachers with stronger qualifications and lower dropout rates than districts with weak unionism. I also find that the recent legal change weakening unionism in four states affects the teacher turnover pattern and teacher quality negatively, confirming unions’ positive role in the US educational system.
This research, therefore, suggests that restricting the legal boundary for unions’ activities may not be the appropriate approach in improving educational outcomes. Rather, promoting union-friendly environments may create more encouraging economic conditions for teachers and provide districts with incentives to select better teachers, eventually raising teacher quality.
You can read the entire study below
The Myth of Unions’ Overprotection of Bad Teachers